1. Technical Field
The present invention relates to a radiation-curable ink composition and relates to an ink jet recording method and recorded matter using the ink composition.
2. Related Art
Recently, radiation-curable inks, which are cured by ultraviolet, electron beams, or other radiation, have been being developed. Such radiation-curable inks can dry rapidly and achieve recording prevented from bleeding of the inks in recording on non-absorbent media that do not or hardly absorb inks, such as plastic, glass, and coated paper. Such radiation-curable inks are composed of, for example, polymerizable monomers, polymerization initiators, pigments, and other additives.
Incidentally, a recorded matter where an image is recorded on a recording medium having flexibility, such as a polyethylene terephthalate resin or a vinyl chloride resin, may be stuck on an article having a curved surface, such as an automobile body. Since, in such purposes, the recorded matter is usually stretched and stuck on an article, it is desirable that the image recorded on the recording medium have a degree of stretch of 100% or more so that cracking and peeling do not occur even if the image is stretched and be provided with durability at the degree of stretch.
In known radiation-curable inks, in order to record flexible images having a degree of stretch of 100% or more, polymerizable monomers, such as a long-chain alkyl acrylate, a phenoxyethyl acrylate, an ethylene oxide adduct of a phenoxyethyl acrylate, or an acrylated amine compound, have been used (for example, see JP-A-2006-199924, JP-A-2007-131754, JP-A-2008-7687, and JP-A-2009-35650).
However, in black inks and yellow inks (in particular, black inks) among the above-mentioned radiation-curable inks that can record flexible images having degrees of stretch of 100% or more, agglomeration spots (gloss unevenness) have occurred on the surfaces of some recorded images. Such a phenomenon does not occur in cyan inks and magenta inks and is specific to black inks and yellow inks.
Furthermore, even in images recorded using radiation-curable inks containing specific polymerizable monomers as described above, cracking occurs within several hours if the images are maintained in the state that the recording media are also stretched (for example, at a degree of stretch of 100%), and problems such that the images are peeled off from the recording media are further caused.